The embodiments described herein relate generally to methods and systems for maintaining a wind turbine having an active flow control system and, more particularly, to methods and system for removing debris from the active flow control system and/or preventing an accumulation of debris within the active flow control system.
Active Flow Control (AFC) is a general term for technologies and/or systems that actively attempt to influence an aerodynamic response of an object in reaction to given in-flow conditions. More specifically, at least some known AFC systems are used to manipulate flow conditions across an airfoil. As used herein, the term “airfoil” refers to a turbine blade, a wing, and/or any other suitable airfoil. Although the embodiments described herein refer to a turbine blade, it should be understood that the embodiments described herein may be used with any suitable airfoil. In contrast to known passive flow control systems that provide substantially constant flow control, known AFC systems enable flow control to be selectively applied to an airfoil. At least some known AFC systems use air distribution systems to manipulate a boundary layer of air flowing across a surface of an airfoil. Known AFC systems include actuators that can be divided in two categories, depending on their net-mass-flow. The first category is zero-net-mass-flow actuators, such as synthetic jet actuators, and the second category is nonzero-net-mass-flow actuators, such as air ejection actuators, which may be steady or unsteady and/or blowing and/or suction actuators.
Because AFC systems are subjected to fluid flows that can contain debris, fouling of AFC perforations and/or apertures by debris is one of the obstacles for wide scale application of AFC on wind turbine blades, aircraft wings, and other airfoils. As used herein, the term “debris” refers to dirt, dust, insects, insect remains, particles, particulates, substances, suspended liquids and/or solids, and/or any other materials that may contact and accumulate in and/or on the wind turbine blades and/or other airfoils. Further, the terms “perforation” and “aperture” can be used interchangeably throughout this application.
In general, fouling of the AFC apertures by debris has an adverse effect on AFC system performance. Further, components, other than the perforations, of at least some known AFC systems are susceptible to fouling as well. For example, in at least some known nonzero-net-mass-flow systems, ambient air, possibly polluted with debris, is drawn into the AFC system to feed the actuators. Such polluted intake air may foul the air distribution system, the actuators, and/or the perforations of the AFC system.
Such fouling of the perforations and/or other components of known AFC systems may alter fluid flows across an airfoil such that the fluid flows deviate from clean-state fluid flows for which the blade is designed to yield. Additionally, fouling on blade surfaces and/or within AFC systems may reduce a power output of a system using airfoils and/or an AFC system, such as a wind turbine. However, manually cleaning each aperture of an AFC system is not practical because of a number of apertures in at least some known AFC systems and/or a duration of time that is required for the wind turbine to be offline for such manual cleaning.
Accordingly, it is desirable to provide a method and/or system for maintaining a wind turbine by cleaning an AFC system and/or preventing fouling of an AFC system. Further, such a method and/or system preferably does not include manual cleaning of the AFC system and/or the blade. Moreover, it is desirable for such method and/or system to use equipment available in a wind turbine having an AFC system.